This present invention relates to the manufacture of electrochemical cells. More particularly, the present invention provides a method to determine unknown material properties of an electrochemical system based on an inverse solution process. Merely by way of example, the invention has been provided with the use of lithium based cells, but it would be recognized that other materials such as zinc, silver, copper and nickel could be designed in the same or like fashion. Additionally, such batteries can be used for a variety of applications such as portable electronics (cell phones, personal digital assistants, music players, video cameras, and the like), power tools, power supplies for military use (communications, lighting, imaging and the like), power supplies for aerospace applications (power for satellites), and power supplies for vehicle applications (hybrid electric vehicles, plug-in hybrid electric vehicles, and fully electric vehicles). The design of such batteries is also applicable to cases in which the battery is not the only power supply in the system, and additional power is provided by a fuel cell, other battery, IC engine or other combustion device, capacitor, solar cell, etc.
Conventional quality control of electrochemical cells general measures the cell performance. Performance targets for electrochemical cells include adequate specific energy/power and energy/power density, cell and module robustness, safety, aging characteristics, lifetime, thermal behavior, and material/shelf life. However, achieving the performance targets is accomplished through trial and error, which is tedious and time consuming. The type and quantity of material for the electrochemistry cell is selected for each component. The resulting battery is tested to determine whether the performance targets have been met, which is generally not the case even after repeated trial and error. The unknown material properties of an electrochemical system often must be determined before selecting the right type and quantity of material and designing the electrochemistry cell. In addition, to determine the unknown material properties also helps cell manufacturer to identify the bottleneck component of the cell performance and improve the specific component.
Several published literature reports attempt to provide systematic and numerical approaches to analyzing and designing batteries. A pioneering approached was described in U.S. Pat. No. 7,945,344, titled “Computational Method for Design and Manufacture of Electrochemical Systems,” in the names of Chia-Wei Wang, Fabio Albano, and Ann Marie Sastry, and assigned to the same Sakti3, Inc. of Ann Arbor Mich., and hereby incorporated by reference in its entirety. Computer simulation can generate relationship between input material properties against one or more performance characteristics in an electrochemical cell. By systematically varying the unknowing material properties and generating the performance characteristics, one can determine the unknown material properties by reducing the difference in the numerical simulation result and the empirical result of the performance characteristics. Although highly successful, certain limitations still exist. As an example, more sophisticated analysis techniques and information are often desirable.
From the above, it is seen that improved techniques for designing and manufacturing electrochemical cells are highly desired.